About limewater test

  1. Carbon dioxide and sulphur dioxide both can turn limewater milky. Either the presence of carbon dioxide and sulphur dioxide can give a positive test result. Why limewater test can be a dedicated test for carbon dioxide?
  2. jcsd
  3. alxm

    alxm 1,845
    Science Advisor

    It isn't. (But if you pass SO2 through it long enough, it will form CaS and become clear again, so in this particular case, it can be a test if you have enough gas.)
  4. If excess amount of carbon dioxide is bubbled into limewater, a clear solution can also be formed (calcium hydrogencarbonate formed). So, excess gas also cannot distinguish between sulphur dioxide and carbon dioxide. I wonder why we usually conclude that carbon dioxide is present if a positive result is shown in limewater test, ignore that it is the presence of sulphur dioxide leading to the positive result.
  5. chemisttree

    chemisttree 3,717
    Science Advisor
    Homework Helper
    Gold Member

    Not true. You will never make a bicarbonate of calcium. It just doesn't happen. ... as a solid anyway.
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